bridge: Fix use of pointer after free in CockpitFsList
bridge: Fix use of pointer after free in CockpitFsList

What happens here, is during an async call, we close the channel.
However the channel has not yet sent its close messages. Because
it's not "ready", and thus frozen. It doesn't send any messages yet.

Once the channel is "ready" (via cockpit_channel_ready()) it thaws
(via cockpit_transport_thaw()) and sends its close message, which
causes the channel to be unreffed by its owner.

Thus the remaining lines of code in on_files_listed() cause a
segfault when accessing self.

This is fixed by correctly holding refs during async calls.

Closes #10273
Fixes #10267

moraleslazaro/cockpit,deryni/cockpit,deryni/cockpit,mvollmer/cockpit,garrett/cockpit,cockpituous/cockpit,mvollmer/cockpit,deryni/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,moraleslazaro/cockpit,andreasn/cockpit,andreasn/cockpit,andreasn/cockpit,garrett/cockpit,cockpituous/cockpit,andreasn/cockpit,cockpit-project/cockpit,mvollmer/cockpit,andreasn/cockpit,cockpituous/cockpit,andreasn/cockpit,cockpit-project/cockpit,cockpituous/cockpit,martinpitt/cockpit,martinpitt/cockpit,martinpitt/cockpit,garrett/cockpit,garrett/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpit-project/cockpit,cockpituous/cockpit,deryni/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,andreasn/cockpit,garrett/cockpit,mvollmer/cockpit,mvollmer/cockpit